In the field of medicine, there are many studies on a photoacoustic apparatus which radiates pulsed light to an object, receives photoacoustic waves generated from the inside of the object using a probe, and changes the internal shape or function of the object into images. In addition, a photoacoustic apparatus has been proposed which can acquire photoacoustic waves and ultrasound echoes from the inside of the object and display an image in real time (PTL 1).
In the photoacoustic apparatus, the positional relation among the object, the optical path, and the probe needs to be correct in order to generate the photoacoustic waves from the inside of the object and correctly acquire the photoacoustic waves using the probe. That is, the object needs to be disposed on the optical path and come into close contact with the probe. The reason is as follows. When the object deviates from the optical path, the photoacoustic wave is not generated. When the object does not come into close contact with the probe, the photoacoustic wave is reflected between the probe and the object and does not reach the probe.
In addition, a photoacoustic apparatus has been proposed which includes a sensor for detecting the contact state between an object and a probe as one of the positional relations (PTL 2).